This is one reason that we feel a shared address space ... is a
fundamental underlying requirement for a high quality Lisp
programming environment.
If I could get a 2 mip Symbolics Lisp machine for under $10K
with very low maintenance costs, good word processing
facilities, good remote and multiple user facilities, and
readily available sources on line, I would want to use one
instead of a Sun-3/52. (I would also want a lot of
Symbolics stock.) I think that Symbolics machines are
absolutely wonderful, and some software activities,
especially debugging, are much, much easier on Lisp machines
than they are on Suns. There are many, many wonderful
things one can do with a shared address space world that one
cannot do so easily without one. Even on Unix, the file
system is really a space of objects shared by all processes.
However, there is still a lot to be said for having
processes in separate address spaces. Have you never wanted
to run simultaneously two almost identical versions of the
same piece of software but been blocked because of package
collisions? (I have often wanted to see why an old piece of
software could do something that an "improved" version
cannot, and been forced to reboot a Lispm just to load in
the old version.) Have you never wished that your Emacs
buffers could be salvaged even though you did something
really awful in Lisp? (Awful isn't confined to doing really
illegal things; I have done merely super stupid things like
tracing PRINT and been wiped out.) Have you never been
chagrined at gross problems like not being able to compile
two files simultaneously? (I don't mean that the latter is
a current problem with anyone's Lisp machine; but the
practice of building Lisp programs in such a way that one
cannot run the code in separate processes simultaneously
because of a shared data structure is widespread.)
The purpose of my original message was to report a message
of basic contentment with a really cheap machine that runs
Lisp well enough for someone who once submitted punched
cards, not to denigrate the magnificence and utility of
Symbolics machines. I wouldn't have sent the message if I
hadn't detected a claim in a preceding message that one
needed a Sun as expensive as a 36xx to run Lisp.
(P.S. Dan, my mailer can't respond to your "from" address.)
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